Planing method and machine for asphalt pavements



y 7, 1966 P. WROCKLOFF 3,251,628

PLANING METHOD AND MACHINE FOR ASPHALT PAVEMENTS Filed April 1, 1963 2 Sheets-Sheet l WE j INVENTOR.

PALMER WROCKLOFF BY M a M ATTORNEYS 3,251,628 PLANING METHOD AND MACHINE FOR ASPHALT PAVEMENTS Filed April 1, 1963 y 1966 P. wRocKLoFF 2 Sheets-Sheet 2 WM [Willi/WM ZZZ/MAM INVEN TOR. PALMER WROCKLOFF ATTORNEYS United States Patent 3,251,628 PLANING METHOD AND MACHINE FOR ASPHALT PAVEMENTS Palmer Wroclrloti, 1363 Emigration St, Salt Lake City 8, Utah Filed Apr. 1, 1963, Ser. No. 269,491 11 Claims. (Cl. 299) This invention has to do with the art of smoothing rippled and rough pavements of asphalt or similar bituminous materials, an art which is generally referred to as planing. It is concerned with providing both a new method and a new machine for the purpose.

Asphalt and similar bituminous materials are subject to softening under the influence of heat. make up a paving composition, they retain this property to a greater or lesser degree depending upon the particular mixture of materials in the composition. In all instances, however, excessive summer heat tends to soften the pavement to an extent which makes for a certain creep or fiow under heavy traffic, resulting in what is often referred to'as a washboard surface. It is for the purpose of smoothing out the rippled and rough contours of such washboard surfaces of roads and other paved areas that planing techniques and machines have been developed.

Heretofore, planing of asphalt-type pavements has been accomplished by, first, heating the rough surface area concerned to a state of semi-plasticity, and, then, while the surface area is in this state of semi-plasticity, by slicing off the bumps or raised areas which make the corrugated or washboard effect. Both the heating and the slicing action are ordinarily accomplished by a single machine resembling a road grader, wherein an elongate heating unit is provided in advance of a road-grading type of blade. This is an expensive operation, because, in addition to the high cost of equipment and fuel, the slowness of. the procedure means that labor costs are excessive.

In the making of the present invention, principal objects were to reduce cost of equipment, eliminate the need for fuel, and speed up the entire operation so that labor costs would be considerably reduced.

In accordance with'the invention, these objects are accomplished by repeatedly applying impact to the effective cutting portion of a grader blade, during a pavement planing operation at ambient temperature, on a continuous basis and at an extremely rapid rate, e.g., above 100,000 impacts per minute, the higher the better, generally speaking. In this way, it is possible to smoothly plane off all irregularities in the surface of a paved area as the blade is moved along such surface at a significant- When used to ly higher rate of travel thanis presently the case with conventional planing equipment.

The machine I have developed for carrying out the method most advantageously comprises a road vehicle of grader type having a grading blade with a cutting edge portion separate from the mold board portion and articulatively secured thereto for oscillating movement longitudinally thereof, i.e., transversely of the machine and of thedirection of travel thereof. The required high frequency impact action is achieved and applied mechanically in a very simple manner. A toothed wheel is driven at a high rate of speed, e.g., from 5,000 to 7,000 r.p.m.s, by any suitable engine, preferably a small internal combustion engine carried by a bracket affixed to the blade.

' A lever, which is pivotally mounted intermediate its ends,

has one arm portion bearing against the toothed circumference of the wheel and the opposite arm portion hearing against a drive bar afiixed to the cutting edge. The teeth of the wheel, the lever arms, and the drive bar are faced at critical wear areas with a hard material, such as tungsten carbide, so as to withstand the tremendous abrasive and pounding action to which they are subjected.

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There is shown in the accompanying drawings a pavement planing machine, which represents what is presently regarded as the best mode of carrying out the genericconcepts of the invention in actual practice. From the detailed disclosure of this presently preferred form of the invention, other more specific objects and features will become apparent.

In the drawings:

FIG. 1 represents a view in side elevation of the pavement planing machine at rest;

FIG. 2, a fragmentary horizontal section taken on the line; 2-2 of FIG. 1 and drawn to a considerably larger sca e;

FIG. 3, a vertical section taken on the line 3--3 of FIG. 2, but drawn to a still larger scale with intermediate portions broken out for convenience of illustration;

FIG. 4, a corresponding view taken on the line 44 of FIG. 2 during operation of the machine;

FIG. 5, a transverse vertical section taken on the line 55 of FIG. 2; and

FIG. 6, a fragmentary horizontal section taken on the line 66 of FIG. 5.

Referring to the drawings:

The vehicle illustrated in FIG. 1 is a road grader of conventional construction provided with a special road grading blade 10 carried by conventional mechanism, in dicated generally at 11, for raising and lowering it relative to a surface to be graded. Although the weight of the blade is normally sufiicient to provide adequate pressure against the surface to be graded, the mechanism 11 may include positive means for pressing the blade against such surface.

A blade of this type is normally twelve feet long and covers a width of about eight feet when properly angled for pavement planing work. This contrasts with a blade covering a width of only thirty to thirty-six inches on the usual pavement planing machine.

In the special grading blade 10, the cutting edge portion 12 is formed independently of the mold board portion 13 and is suspended therefrom by a series of rigid links 14, whose opposite ends are pivotally connected, as by pins 15, FIG. 4, to cutting edge portion and mold board portion, respectively.

In this manner, the cutting edge portion 12 is arranged to be oscillated laterally and vertically relative to the mold board portion 13. Normally, when the blade 10 is resting or is positively pressed against an asphalt pavement to be planed, the back 12a of the cutting edge portion bears against the lower edge of the mold board portion, as in FIG. 3.

'In order to carry out the method of the invention, means for rapidly applying successive impacts to the cutting edge portion 12 longitudinally thereof (the direction in which such cutting edge is free tomove) are provided. Such means are advantageously mechanical, and, except for a drive bar 16 projecting rearward'ly from fixed securement to cutting edge portion 12, are desirably mounted on the back of and are carried by the mold board portion.

As illustrated, the impact-applying means comprises a lever 17 mounted on a bracket platform 18, which projects rearwardly from rigid securement to the back of mold board portion 13. Such lever is pivotally secured, intermediate its ends, between a pair of upstanding ears 19, FIG. 5, by a pin 20, FIG. 4, and has a work arm 17a extending downwardly into operative association with drive bar 16, see FIG. 6 and a power arm 17b extending upwardly. Means are provided for repeatedly applying impact to power arm 17 b at an extremely rapid rate and in a direction effective to move work arm 17a toward drive bar 16.

Lever 17 is arranged so that its work arm 17a normally rests against or in proximity to drive bar 16. Thus, when its power arm is struck in a direction opposite to the specified direction, such drive bar is struck in the specified direction and the cutting edge portion 12 is impelled to execute an oscillating stroke longitudinally of the blade, laterally and'vertically with respect to themachine as a whole.

Any suitable means may be provided to repeatedly apply impact to power arm 17b of lever 17 at the required:

rate of speed, although it is preferred to utilize a toothed wheel 20 rotated by a prime mover in the form of a small, four cylinder, internal combustion engine 21 of from twenty to twenty five horsepower, or in the form of an equivalent electric motor powered by a suitable generator. As illustrated, both the wheel 20 and engine 21 are conveniently mounted on bracket platform 18 and are carried by mold board portion 12 of the grader blade 10. Wheel 20 and driven pulleys 22 are fixed to a shaft 23 journaled in bearings 24 and 25. Drive pulleys 26, FIG. 2, of engine 21 are connected by V- belts 27 to driven pulleys 22.

Lever 17 is so arranged that its power arm 17b protrudes at least partially into a valley between adjacent teeth 20a of wheel 20, see FIG. 3, when blade rests upon or is pressed downwardly against the pavement to be planed. Thus, as indicated in FIG. 4, it is pushed outwardly of such valley and tends to drop into succeeding valleys as it rides on the toothed circumference of the wheel. From this standpoint, lever 17 resembles a pawl and wheel a ratchet, the teeth 20a being formed similarly to the teeth of a ratchet wheel. I As wheel 20 rotates at a high rate of speed, e.g.

60007000 r.p.m., the power arm 17b of lever 17 is forcefully and repeatedly struck at an exceptionally high rate, depending upon the number of teeth on such wheel. With 23 teeth, as illustrated, and at 6000 r.p.m., the impact rate will be 138,000 per minute. With more teeth, the impact rate will be increased proportionately. Work arm 17a will apply the impacts directly to drive bar 16.

For purposes of support, the outer end 16a of drive bar 16 is pivotally secured by a link 28 to the underside of bracket platform 18.

In view of the rapidity and force of the impacts, it is necessary that at least the teeth 20a be faced with tungsten carbide or some equivalent material to withstand the abrasive and pounding action. It is also advisable to similarly face contacting portions of the lever arms and of the drive bar. This is conveniently accomplished by welding.

In the use of this machine, the effective width of the blade, when angled diagonally, is, as aforementioned, about eight feet in comparison to from thirty to thirtysix inches for a standard pavement planer. It can cover from 2640 to 5280 feet per hour or thereabouts as compared to from 720 to 1200 feet per hour for a standard pavement planer.

The amplitude of stroke is, of course, governed by the character of the pavement concerned. The stroke is a forceful driving action against substantially immovable resistance. The cutting edge portion of the grader blade functions almost like a chisel as it is being drawn forwardly under these extremely rapidly repeated impacts.

Whereas there is here illustrated and specifically described a certain preferred procedure and construction of apparatus which is presently regarded as the best mode of carrying out the invention, it should be understood that various changes may be made and other constructions adopted without, departing from the inventive subject matter particularly pointed out and claimed herebelow.

I claim:

1. In an asphalt pavement planing machine which includes a vehicle of road grader type having a grader blade extending transversely of the line of travel of the vehicle, the improvement comprising:

a cutting edge portion and a mold board portion of the grader blade formed independently of each other; means articulatively suspending the cutting edge por- 5 tion from the mold board portion, so said cutting edge portion is free to move longitudinally in opposite directions;

and impact-applying means, comprising a lever having power and work arms,

a drive bar secured to the cuttingedge portion of the grader blade in the line of action of said work arm,

a circumferentially toothed wheel, against the toothed portions of which said power arm normally rests, the teeth of said wheel being adapted to successively strike said power arm at an extremely rapid rate and in a direction effective to move said work arm toward and forcefully against said drive bar,

and means for rotating said wheel at high speed.

2. The improvement of claim 1, wherein the means suspending the cutting edge portion from the mold board portion comprises a series of articulate suspension elements.

3. The improvement of claim 2, wherein the suspension elements are rigid links pivotally connected at their opposite ends to cutting edge portion and mold board portion, respectively.

4. The improvement of claim 1, wherein the lever is pivotally mounted in fixed position intermediate its ends, so that one end portion forms the power arm and the opposite end portion the work arm.

5. The improvement of claim 1, wherein the means for rotating the toothed wheel is a prime mover; and wherein the lever, the toothed wheel, and the prime mover are all carried by the mold board portion of the grader blade,

6. The improvement of claim 1, wherein at least the teeth of the toothed wheel are faced with tungsten carbide.

7. The improvement of claim 1, wherein the drive bar is secured to the cutting edge portion, of the grader blade, but the other components of the impact-applying means are carried by the mold board portion.

8. A method of planing a finished asphalt pavement, comprising:

advancing a road grading blade, having a cutting edge portion separate and suspended from a mold board portion, across and in substantially continuous pressure contact with the surface of said pavement at ambient temperature to cut off portions of the pavement surface,

and applying impacts to the cutting edge portion of said blade, longitudinally of said cutting edge portion, at an extremely rapid rate during said advancement of said blade.

9. In combination, a road vehicle;

an elongate road-grading blade suspended from said vehicle and having a cutting edge in road-scraping position and free to move longitudinally in opposite directions;

and impact-applying means for said cutting edge, comprising a lever having power and work arms,

a drive bar secured to said cutting edge in the line of action of said work arm,

a circumferentially toothed wheel, against the toothed portion of which said power arm normally rests, the teeth of said wheel being adapted to successively strike said power arm at an extremely rapid rate and in a direction effective to move said Work arm toward and forcefully against said drive bar,

and means for rotating said wheel at high speed,

all of the components except said drive bar being mounted independently of said cutting edge.

10. In combination, an elongate vibratory element of the nature of the cutting edge portion of a road-grading blade;

means for suspending said element from a non-vibratory mounting so that it is free to move longitudinally in opposite directions; and impact-applying means for said element, comprising a'lever having power and work arms, a drive bar secured to said element in the line of action of said work arm, a circumferentially toothed wheel, against the toothed portion of Which said power arm normally rests, the teeth of said wheel being adapted to successively st-rike said power arm at an extremely rapid rate in a direction effective to move said work arm toward and forcefully against said drive bar.

and means for rotating said wheel at high speed, all

of the components except said drive bar being mounted independently of said element. 11. In an asphalt pavement planing machine which in eludes a vehicle of road grader type having a grader blade extending transversely of the line of travel of the vehicle, the improvement comprising:

a cutting edge portion and a mold board portion of the grader blade formed independently of each other; means articulatively suspending the cutting edge portion from the mold boa-rd portion, so said cutting edge portion is free to move longitudinally in op posite directions;

a circumferentially toothed wheel;

means for rotating said wheel at high speeds;

and motion transmitting means adapted to be engaged by the toothed portions of the wheel and to transmit the impact forces of said teeth to said cutting edge portion when said wheel is rotated, to effectively and repeatedly move said cutting edge portion in one of said longitudinal directions.

References Cited by the Examiner ERNEST R. PURSER, Primary Examiner.

BENJAMIN HERSH, CHARLES E. OCONNELL,

Examiners. 

8. A METHOD OF PLANING A FINISHED ASPHALT PAVEMENT, COMPRISING: ADVANCING A ROAD GRADING BLADE, HAVING A CUTTING EDGE PORTION SEPARATE AND SUSPENDED FROM A MOLD BOARD PORTION, ACROSS AND IN SUBSTANTIALLY CONTINUOUS PRESSURE CONTACT WITH THE SURFACE OF SAID PAVEMENT AT AMBIENT TEMPERATURE TO CUT OFF PORTIONS OF THE PAVEMENT SURFACE, AND APPLYING INPACTS TO THE CUTTING EDGE PORTION OF SAID BLADE, LONGITUDINALLY OF SAID CUTTING EDGE PORTION, AT AN EXTREMELY RAPID RATE DURING SAID ADVANCEMENT OF SAID BLADE. 